Figure 5: Gene expression profiles of cartilage in treated and control porcine knees. At 12 weeks after transplantation of the human umbilical cord mesenchymal stem cells and hyaluronic acid, mRNA extractions from treated or nontreated cartilages of the two pigs were examined for their gene expression profiles by using real-time polymerase chain reaction. (a) Pig 1; (b) pig 2. The genes included the transcription factor aggrecan, type-II collagen (COL2A1), type-X collagen (COL10A1), and the stress-related gene MMP13, with glyceraldehyde-3-phosphate dehydrogenase serving as an internal control. Threshold cycle (Ct) values were obtained for each target gene and glyceraldehyde-3-phosphate dehydrogenase as a control for normalization, and fold expression (relative to control knees) was measured using the 2−ΔΔCt method. **P < 0.01, ***P < 0.001. RQ: relative quantification